Apple sells an application suite for OS X called OS X Server, for use on servers. It includes tools to facilitate management of workgroups of OS X machines, and to provide network services. It is sold separately through the Mac App Store as a single item; in the past it was sold separately or preinstalled on dedicated server computers.

The latest version of OS X is 10.10 "Yosemite", which was released to the public on October 16, 2014.

Throughout the early 1990s, Apple had tried to create a "next-generation" OS through the Taligent, Copland and Gershwin projects, although these were eventually abandoned.[20] This led Apple to purchase NeXT in 1996, allowing NeXTSTEP, then called OPENSTEP, to serve as the basis for Apple's next generation OS.[21] This purchase also led to Steve Jobs returning to Apple as interim CEO, and later CEO, shepherding the transformation of the programmer-friendly OPENSTEP into a system that would be adopted by Apple's primary market of home users and creative professionals. The project was first code named "Rhapsody" and then officially named "Mac OS X".[22]

Mac OS X was launched for PowerPC-based Macs. In 2006, the first Intel Macs had a specialized version of 10.4 "Tiger".[23] In 2007, 10.5 "Leopard" was the first to run on both PowerPC and Intel Macs with the use of Universal Binaries.[24]10.6 "Snow Leopard" was the first version of OS X to drop support for PowerPC Macs.[25]

Mac OS X Server 1.x is incompatible with software designed for the original Mac OS and has no support for Apple's own IEEE 1394 (FireWire) interface. Mac OS X 10.x includes more backward compatibility through Classic and more functionality by introducing the Carbon API as well as FireWire support. As the operating system evolved, it moved away from the legacy Mac OS to an emphasis on new "digital lifestyle" applications such as the iLife suite, enhanced business applications (iWork), and integrated home entertainment (the Front Row media center).[26] Each version also included modifications to the general interface, such as the brushed metal appearance added in version 10.3, the non-pinstriped titlebar appearance in version 10.4, and in 10.5 the removal of the previous brushed metal styles in favor of the "Unified" gradient window style.[27][28]

In 2012, with the release of OS X 10.8, the "Mac" prefix was officially dropped in all references to the operating system name within its web site.[29]

Description

OS X is the tenth major version of Apple's operating system for Macintosh computers. Previous Macintosh operating systems were named using Arabic numerals, e.g. Mac OS 8 and Mac OS 9. The letter X in OS X's name refers to the number 10, a Roman numeral. It is therefore correctly pronounced "ten" /ˈtɛn/ in this context.[12][30] However, a common mispronunciation is "X" /ˈɛks/.[31]

OS X's core is a POSIX compliant operating system (OS) built on top of the XNUkernel, with standard Unix facilities available from the command line interface. Apple has released this family of software as a free and open source operating system named Darwin. On top of Darwin, Apple layered a number of components, including the Aqua interface and the Finder, to complete the GUI-based operating system which is OS X.[32]

OS X introduced a number of new capabilities to provide a more stable and reliable platform than its predecessor, Mac OS 9. For example, pre-emptive multitasking and memory protection improved the system's ability to run multiple applications simultaneously without them interrupting or corrupting each other.[33] Many aspects of OS X's architecture are derived from OPENSTEP, which was designed to be portable, to ease the transition from one platform to another. For example, NeXTSTEP was ported from the original 68k-based NeXT workstations to x86 and other architectures before NeXT was purchased by Apple,[34] and OPENSTEP was later ported to the PowerPC architecture as part of the Rhapsody project.

The most visible change was the Aqua theme. The use of soft edges, translucent colors, and pinstripes—similar to the hardware design of the first iMacs—brought more texture and color to the user interface when compared to what OS 9 and OS X Server 1.0's "Platinum" appearance had offered. According to John Siracusa, an editor of Ars Technica, the introduction of Aqua and its departure from the then conventional look "hit like a ton of bricks."[35]Bruce Tognazzini (who founded the original Apple Human Interface Group) said that the Aqua interface in Mac OS X v10.0 represented a step backwards in usability compared with the original Mac OS interface.[36][37] Third-party developers started producing skins for customizable applications and other operating systems which mimicked the Aqua appearance. To some extent, Apple has used the successful transition to this new design as leverage, at various times threatening legal action against people who make or distribute software with an interface the company says is derived from its copyrighted design.[38]

The architecture of OS X incorporates a layered design.[39] The layered frameworks aid rapid development of applications by providing existing code for common tasks.[40]

The Darwin sub-system in Mac OS X is in charge of managing the filesystem, which includes the Unix permissions layer. In 2003 and 2005, two Macworld editors expressed criticism of the permission scheme; Ted Landau called misconfigured permissions "the most common frustration" in Mac OS X, while Rob Griffiths suggested that some users may even have to reset permissions every day, a process which can take up to 15 minutes.[42] More recently, another Macworld editor, Dan Frakes, called the procedure of repairing permissions vastly overused.[43] He argues that OS X typically handles permissions properly without user interference, and resetting permissions should just be tried when problems emerge.[44]

Mac applications may be installed by the user from any source, or from the Mac App Store, a marketplace of software maintained by Apple. All App Store applications run within a 'sandbox', restricting their ability to communicate with other programs or modify the core operating system. This provides increased user security but restricts the features they can offer.

Distribution and languages

As of September 2011, OS X is the second-most-active general-purpose client operating system in use on the World Wide Web, (after Microsoft Windows), with an 8.45% usage share according to statistics compiled by W3Counter.[45] It is the most successful Unix-like desktop operating system on the web, estimated at over 5 times the usage of Linux (which has 1.5%).[45]

There are twenty-two "System Languages" available for the user at the moment of installation (the "system language" is the entire operating system environment). As of Mac OS X Lion, the languages are Arabic, Chinese (Simplified), Chinese (Traditional), Czech, Danish, Dutch, English, Finnish, French, German, Hebrew, Hungarian, Italian, Japanese, Korean, Norwegian, Polish, Portuguese (Brazilian), Portuguese (European), Russian, Spanish, Swedish and Turkish. Input methods for typing in dozens of scripts can be chosen independently of the system language.[46]

Compatibility

Software

The APIs that OS X inherited from OpenStep are not backward compatible with earlier versions of Mac OS. These APIs were created as the result of a 1993 collaboration between NeXT Computer and Sun Microsystems and are now referred to by Apple as Cocoa. This heritage is highly visible for Cocoa developers, since the "NS" prefix is ubiquitous in the framework, standing variously for Nextstep or NeXT/Sun. The official OpenStep API, published in September 1994, was the first to split the API between Foundation and Application Kit and the first to use the "NS" prefix.[34] Apple's Rhapsody project would have required all new development to use these APIs, causing much outcry among existing Mac developers. All Mac software that did not receive a complete rewrite to the new framework would run in the equivalent of the Classic environment. To permit a smooth transition from Mac OS 9 to (Mac) OS X, the CarbonApplication Programming Interface (API) was created. Applications written with Carbon can be executed natively on both systems. Carbon was not included in the first product sold as "Mac OS X": Mac OS X Server (now referred to as Mac OS X Server 1.x).[citation needed]

OS X also used to support the Java Platform as a "preferred software package"—in practice this means that applications written in Java fit as neatly into the operating system as possible while still being cross-platform compatible, and that graphical user interfaces written in Swing look almost exactly like native Cocoa interfaces. Traditionally, Cocoa programs have been mostly written in Objective-C, with Java as an alternative. However, on July 11, 2005, Apple announced that "features added to Cocoa in Mac OS X versions later than 10.4 will not be added to the Cocoa-Java programming interface."[47]

Since OS X is POSIX compliant, many software packages written for the *BSDs, Linux, or other Unix-like systems can be recompiled to run on it. Projects such as Homebrew, Fink, MacPorts and pkgsrc provide pre-compiled or pre-formatted packages. From version 10.3 to version 10.7, OS X included X11.app, Apple's version of the X Window System graphical interface for Unix applications, as an optional component during installation.[48] Up to and including Mac OS X v10.4 (Tiger), Apple's implementation was based on the X11 LicensedXFree86 4.3 and X11R6.6. All bundled versions of X11 feature a window manager which is similar to the OS X look-and-feel and has fairly good integration with Mac OS X, also using the native Quartz rendering system. Earlier versions of OS X (in which X11 has not been bundled) can also run X11 applications using XDarwin. With the introduction of version 10.5 Apple switched to the X.org variant of X11.[49] Version Mac OS X 10.7 "Lion" uses X.org Server version 1.10.x[50] Starting with OS X Mountain Lion, X11 is not bundled in OS X; instead, it has to be installed from, for example, the open source XQuartz project.[51]

Hardware

For the early releases of Mac OS X, the standard hardware platform supported was the full line of Macintosh computers (laptop, desktop, or server) based on PowerPC G3, G4, and G5 processors. Later versions discontinued support for some older hardware; for example, Panther does not support "beige" G3s,[52] and Tiger does not support systems that pre-date Apple's introduction of integrated FireWire ports (the ports themselves are not a functional requirement). Mac OS X v10.5 "Leopard", introduced October 2007, has dropped support for all PowerPC G3 processors and for PowerPC G4 processors with clock rates below 867 MHz. Mac OS X v10.6 "Snow Leopard" supports Macs with Intel processors, not PowerPC. Mac OS X 10.7 "Lion" requires a Mac with an Intel Core 2 Duo or newer processor.[citation needed]

Tools such as XPostFacto and patches applied to the installation disc have been developed by third parties to enable installation of newer versions of Mac OS X on systems not officially supported by Apple. This includes a number of pre-G3 Power Macintosh systems that can be made to run up to and including Mac OS X 10.2 Jaguar, all G3-based Macs which can run up to and including Tiger, and sub-867 MHz G4 Macs can run Leopard by removing the restriction from the installation DVD or entering a command in the Mac's Open Firmware interface to tell the Leopard Installer that it has a clock rate of 867 MHz or greater. Except for features requiring specific hardware (e.g. graphics acceleration, DVD writing), the operating system offers the same functionality on all supported hardware.[citation needed]

PowerPC versions of Mac OS X prior to Leopard retain compatibility with older Mac OS applications by providing an emulation environment called Classic, which allows users to run Mac OS 9 as a process within Mac OS X, so that most older applications run as they would under the older operating system. Classic is not supported on Intel-based Macs or in Mac OS X v10.5 "Leopard", but users still requiring Classic applications on Intel Macs can use the SheepShaver emulator to run Mac OS 9 on top of Leopard.[citation needed]

As all Macintosh components are either generic or branded and available on the open market - for example Intel processors, Hitachi hard drives, Intel/Radeon/Nvidia graphics cards[53] - there are small communities that install OS X on non-Apple IBM PC compatible computers; these are referred to as Hackintoshes. This violates the EULA,[54] but communities such as tonymacx86 that cater to personal users, who do not install for resale and profit, have been free to operate since 2010,[55] around the time of the PowerPC to Intel switchover, which made the it possible to begin with.[56] Psystar, a business that did attempt to profit from selling OSX on non-Apple certified hardware, was sued by Apple in 2008.[57]

PowerPC–Intel transition

In April 2002, eWeek announced a rumor that Apple had a version of Mac OS X code-named Marklar, which ran on Intel x86 processors. The idea behind Marklar was to keep Mac OS X running on an alternative platform should Apple become dissatisfied with the progress of the PowerPC platform.[58] These rumors subsided until late in May 2005, when various media outlets, such as The Wall Street Journal[59] and CNET,[60] announced that Apple would unveil Marklar in the coming months.

On June 6, 2005, Steve Jobs confirmed these rumors when he announced in his keynote address at the annual Apple Worldwide Developers Conference that Apple would be making the transition from PowerPC to Intel processors over the following two years, and that Mac OS X would support both platforms during the transition. Jobs also confirmed rumors that Apple had versions of Mac OS X running on Intel processors for most of its developmental life. The last time that Apple switched CPU families—from the Motorola 68K CPU to the IBM/Motorola PowerPC—Apple included a Motorola 68K emulator in the new OS that made almost all 68K software work automatically on the new hardware. Apple had supported the 68K emulator for 11 years, but stopped supporting it during the transition to Intel CPUs. Included in the new OS for the Intel-based Macs was Rosetta, a binary translation layer which enabled software compiled for PowerPC Mac OS X to run on Intel Mac OS X machines. Apple dropped support for Classic mode on the new Intel Macs. Third party emulation software such as Mini vMac, Basilisk II and SheepShaver provided support for some early versions of Mac OS. A new version of Xcode and the underlying command-line compilers supported building universal binaries that would run on either architecture.[61]

PowerPC-only software was supported with Rosetta, though some applications eventually had to be rewritten to run properly on the newer OS X for Intel. Apple initially encouraged developers to produce universal binaries with support for both PowerPC and x86.[62] There is a performance penalty when PowerPC binaries run on Intel Macs through Rosetta. Moreover, some PowerPC software, such as kernel extensions and System Preferences plugins, are not supported on Intel Macs. Some PowerPC applications would not run on Intel OS X at all. Plugins for Safari need to be compiled for the same platform as Safari, so when Safari is running on Intel it requires plug-ins that have been compiled as Intel-only or universal binaries, so PowerPC-only plug-ins will not work.[63] While Intel Macs are able to run PowerPC, x86, and universal binaries; PowerPC Macs support only universal and PowerPC builds.[citation needed]

Support for the PowerPC platform was dropped after Mac OS X 10.5. Such cross-platform capability already existed in Mac OS X's lineage; OpenStep was ported to many architectures, including x86, and Darwin included support for both PowerPC and x86. Apple stated that Mac OS X would not run on Intel-based personal computers aside from its own, but a hacked version of the OS compatible with conventional x86 hardware was developed by the OSx86 community.[64]

On June 8, 2009, Apple announced at its Worldwide Developers Conference that Snow Leopard (version 10.6) would drop support for PowerPC processors and be Intel-only.[65] However, Rosetta is still available in Snow Leopard; it is not installed by default, but it is available on the installation DVD as an installable add-on and is installed automatically via the Internet when first attempting to run a PowerPC-based application.[citation needed]

On all versions from (and including) Lion, Rosetta is no longer available.[citation needed]

Features

One of the major differences between the previous versions of Mac OS and OS X was the addition of the Aqua GUI, a graphical user interface with water-like elements. Every window element, text, graphic, or widget is drawn on-screen using spatial anti-aliasing technology.[66]ColorSync, a technology introduced many years before, was improved and built into the core drawing engine, to provide color matching for printing and multimedia professionals.[67] Also, drop shadows were added around windows and isolated text elements to provide a sense of depth. New interface elements were integrated, including sheets (document modal dialog boxes attached to specific windows) and drawers.[citation needed]

Apple has continued to change aspects of the OS X appearance and design, particularly with tweaks to the appearance of windows and the menu bar. One example of a UI behavioral change is that previewed video and audio files no longer have progress bars in column view; instead, they have mouse-over start and stop buttons as of 10.5.[citation needed]

The human interface guidelines published by Apple for Mac OS X are followed by many applications, giving them consistent user interface and keyboard shortcuts.[68] In addition, new services for applications are included, which include spelling and grammar checkers, special characters palette, color picker, font chooser and dictionary; these global features are present in every Cocoa application, adding consistency. The graphics system OpenGL composites windows onto the screen to allow hardware-accelerated drawing. This technology, introduced in version 10.2, is called Quartz Extreme, a component of Quartz. Quartz's internal imaging model correlates well with the Portable Document Format (PDF) imaging model, making it easy to output PDF to multiple devices.[67] As a side result, PDF viewing and creating PDF documents from any application are built-in features.[69]

In version 10.3, Apple added Exposé, a feature which includes three functions to help accessibility between windows and desktop. Its functions are to instantly display all open windows as thumbnails for easy navigation to different tasks, display all open windows as thumbnails from the current application, and hide all windows to access the desktop.[70] Also, FileVault was introduced, which is an optional encryption of the user's files with Advanced Encryption Standard (AES-128).[71]

Features introduced in version 10.4 include Automator, an application designed to create an automatic workflow for different tasks;[72]Dashboard, a full-screen group of small applications called desktop widgets that can be called up and dismissed in one keystroke;[73] and Front Row, a media viewer interface accessed by the Apple Remote.[74] Moreover, the Sync Services were included, which is a system that allows applications to access a centralized extensible database for various elements of user data, including calendar and contact items. The operating system then managed conflicting edits and data consistency.[75]

As of version 10.5, all system icons are scalable up to 512×512 pixels, to accommodate various places where they appear in larger size, including for example the Cover Flow view, a three-dimensional graphical user interface included with iTunes, the Finder, and other Apple products for visually skimming through files and digital media libraries via cover artwork. This version includes Spaces, a virtual desktop implementation which enables the user to have more than one desktop and display them in an Exposé-like interface.[76] Mac OS X v10.5 includes an automatic backup technology called Time Machine, which provides the ability to view and restore previous versions of files and application data;[77] and Screen Sharing was built in for the first time.[78]

Finder is a file browser allowing quick access to all areas of the computer, which has been modified throughout subsequent releases of Mac OS X.[79][80]Quick Look is part of Mac OS X Leopard's Finder. It allows for dynamic previews of files, including videos and multi-page documents, without opening their parent applications. Spotlight search technology, which is integrated into the Finder since Mac OS X Tiger, allows rapid real-time searches of data files; mail messages; photos; and other information based on item properties (meta data) and/or content.[81][82] Mac OS X makes use of a Dock, which holds file and folder shortcuts as well as minimized windows.

With the exception of Mac OS X Server 1.0 and the original public beta, OS X versions were named after big cats until version 10.9, when Apple switched to using California locations. Prior to its release, version 10.0 was code named "Cheetah" internally at Apple, and version 10.1 was code named internally as "Puma". After the immense buzz surrounding version 10.2, codenamed "Jaguar", Apple's product marketing began openly using the code names to promote the operating system. 10.3 was marketed as "Panther", 10.4 as "Tiger", 10.5 as "Leopard", 10.6 as "Snow Leopard", 10.7 as "Lion", 10.8 as "Mountain Lion", and 10.9 as "Mavericks". "Panther", "Tiger" and "Leopard" are registered as trademarks of Apple, but "Cheetah", "Puma" and "Jaguar" have never been registered. Apple has also registered "Lynx" and "Cougar" as trademarks, though these were allowed to lapse.[97] Computer retailer Tiger Direct sued Apple for its use of the name "Tiger". On May 16, 2005 a US federal court in the Southern District of Florida ruled that Apple's use did not infringe on Tiger Direct's trademark.[98]

Public Beta: "Kodiak"

On September 13, 2000 Apple released a $29.95[99] "preview" version of Mac OS X (internally codenamed Kodiak) in order to gain feedback from users.

The "PB" as it was known marked the first public availability of the Aqua interface and Apple made many changes to the UI based on customer feedback. Mac OS X Public Beta expired and ceased to function in Spring 2001.[100]

Version 10.0: "Cheetah"

On March 24, 2001, Apple released Mac OS X v10.0 (internally codenamed Cheetah).[101] The initial version was slow, incomplete, and had very few applications available at the time of its launch, mostly from independent developers. While many critics suggested that the operating system was not ready for mainstream adoption, they recognized the importance of its initial launch as a base on which to improve. Simply releasing Mac OS X was received by the Macintosh community as a great accomplishment, for attempts to completely overhaul the Mac OS had been underway since 1996, and delayed by countless setbacks. Following some bug fixes, kernel panics became much less frequent.[citation needed]

Version 10.1: "Puma"

Later that year on September 25, 2001, Mac OS X v10.1 (internally codenamed Puma) was released. It featured increased performance and provided missing features, such as DVD playback. Apple released 10.1 as a free upgrade CD for 10.0 users, in addition to the US$129 boxed version for people running Mac OS 9. It was discovered that the upgrade CDs were full install CDs that could be used with Mac OS 9 systems by removing a specific file; Apple later re-released the CDs in an actual stripped-down format that did not facilitate installation on such systems.[102] On January 7, 2002, Apple announced that Mac OS X was to be the default operating system for all Macintosh products by the end of that month.[103]

Version 10.2: "Jaguar"

On August 23, 2002,[104] Apple followed up with Mac OS X v10.2 "Jaguar", the first release to use its code name as part of the branding.[105] It brought great raw performance improvements, a sleeker look, and many powerful user-interface enhancements (over 150, according to Apple[106] ), including Quartz Extreme for compositing graphics directly on an ATIRadeon or NvidiaGeForce2 MX AGP-based video card with at least 16 MB of VRAM, a system-wide repository for contact information in the new Address Book, and an instant messaging client named iChat.[107] The Happy Mac which had appeared during the Mac OS startup sequence for almost 18 years was replaced with a large grey Apple logo with the introduction of Mac OS X v10.2.

Version 10.3: "Panther"

Mac OS X v10.3 "Panther" was released on October 24, 2003. In addition to providing much improved performance, it also incorporated the most extensive update yet to the user interface. Panther included as many or more new features as Jaguar had the year before, including an updated Finder, incorporating a brushed-metal interface, Fast user switching, Exposé (Window manager), FileVault, Safari, iChat AV (which added videoconferencing features to iChat), improved Portable Document Format (PDF) rendering and much greater Microsoft Windows interoperability.[108] Support for some early G3 computers such as "beige" Power Macs and "WallStreet" PowerBooks was discontinued.[citation needed]

Version 10.4: "Tiger"

Mac OS X v10.4 "Tiger" was released on April 29, 2005. Apple stated that Tiger contained more than 200 new features.[109] As with Panther, certain older machines were no longer supported; Tiger requires a Mac with 256MB and a built-in FireWire port.[52] Among the new features, Tiger introduced Spotlight, Dashboard, Smart Folders, updated Mail program with Smart Mailboxes, QuickTime 7, Safari 2, Automator, VoiceOver, Core Image and Core Video. The initial release of the Apple TV used a modified version of Tiger with a different graphical interface and fewer applications and services. On January 10, 2006, Apple released the first Intel-based Macs along with the 10.4.4 update to Tiger. This operating system functioned identically on the PowerPC-based Macs and the new Intel-based machines, with the exception of the Intel release dropping support for the Classic environment.[110]

Version 10.5: "Leopard"

Mac OS X v10.5 "Leopard" was released on October 26, 2007. It was called by Apple "the largest update of Mac OS X". It brought more than 300 new features.[111] Leopard supports both PowerPC- and Intel x86-based Macintosh computers; support for the G3 processor was dropped and the G4 processor required a minimum clock rate of 867 MHz, and at least 512 MB of RAM to be installed. The single DVD works for all supported Macs (including 64-bit machines). New features include a new look, an updated Finder, Time Machine, Spaces, Boot Camp pre-installed,[112] full support for 64-bit applications (including graphical applications), new features in Mail and iChat, and a number of new security features. Leopard is an Open Brand UNIX 03 registered product on the Intel platform. It was also the first BSD-based OS to receive UNIX 03 certification.[3][113] Leopard dropped support for the Classic Environment and all Classic applications.[114] It was the final version of Mac OS X to support the PowerPC architecture.

Version 10.6: "Snow Leopard"

Mac OS X v10.6 "Snow Leopard" was released on August 28, 2009. Rather than delivering big changes to the appearance and end user functionality like the previous releases of Mac OS X, Snow Leopard focused on "under the hood" changes, increasing the performance, efficiency, and stability of the operating system. For most users, the most noticeable changes were: the disk space that the operating system frees up after a clean install compared to Mac OS X 10.5 Leopard, a more responsive Finder rewritten in Cocoa, faster Time Machine backups, more reliable and user friendly disk ejects, a more powerful version of the Preview application, as well as a faster Safari web browser. Snow Leopard only supported machines with Intel CPUs, required at least 1 GB of RAM, and dropped default support for applications built for the PowerPC architecture (Rosetta could be installed as an additional component to retain support for PowerPC-only applications).[115]

Version 10.7: "Lion"

Mac OS X v10.7 "Lion" was released on July 20, 2011. It brought developments made in Apple's iOS, such as an easily navigable display of installed applications (Launchpad) and a greater use of multi-touch gestures, to the Mac. This release removed Rosetta, making it incapable of running PowerPC applications.[citation needed]

Changes made to the GUI (Graphical User Interface) include the Launchpad (similar to the home screen of iOS devices), auto-hiding scrollbars that only appear when they are being used, and Mission Control, which unifies Exposé, Spaces, Dashboard, and full-screen applications within a single interface.[117] Apple also made changes to applications: they resume in the same state as they were before they were closed (similar to iOS). Documents auto-save by default.[citation needed]

Version 10.8: "Mountain Lion"

OS X v10.8 "Mountain Lion" was released on July 25, 2012.[92] It incorporates some features seen in iOS 5, which include Game Center, support for iMessage in the new Messages messaging application, and Reminders as a to-do list app separate from iCal (which is renamed as Calendar, like the iOS app). It also includes support for storing iWork documents in iCloud.[118]Notification Center, which makes its debut in Mountain Lion, is a desktop version similar to the one in iOS 5.0 and higher. Application pop-ups are now concentrated on the corner of the screen, and the Center itself is pulled from the right side of the screen. Mountain Lion also includes more Chinese features including support for Baidu as an option for Safari search engine, QQ, 163.com and 126.com services for Mail, Contacts and Calendar, Youku, Tudou and Sina Weibo are integrated into share sheets.[119]

Version 10.9: "Mavericks"

OS X 10.9 "Mavericks" was released on October 22, 2013. This is a free upgrade to all users running OS X Snow Leopard or later, and has a 64-bit Intel processor.. Its changes include the addition of the previously iOS-only Maps and iBooks applications, improvements to the Notification Center, enhancements to several applications, and many under-the-hood improvements.[120]

Version 10.10: "Yosemite"

OS X 10.10 "Yosemite" was released on October 16, 2014. Apple's showcase new feature in Yosemite is Handoff, which enables users with iPhones running iOS 8.1 or later to answer phone calls, receive and send SMS messages, and complete unfinished iPhone emails on their Mac.

Version 10.11: "El Capitan"

OS X 10.11 "El Capitan" was announced on June 8, 2015. Apple's described this release as containing "Refinements to the Mac Experience" and "Improvements to System Performance" rather than new features. Refinements include public transport built in to the Maps application, GUI improvements to the Notes application, as well as adopting San Francisco as the system font.

Updating methods

OS X can be updated using the Mac App Store. Until OS X Mountain Lion, the updating method was to use the Apple Software Update.

Software Update is a software tool by Apple Inc. that installs the latest version of Apple software on computers running OS X. It was originally introduced to Mac users in Mac OS 9. A Windows version has been available since the introduction of iTunes 7, under the name Apple Software Update. Software Update automatically informs users of new updates. The program is part of the CoreServices in OS X. Software Update can be set to check for updates daily, weekly, monthly, or not at all; in addition, it can download and store the associated .pkg file (the same type used by Installer) to be installed at a later date and maintains a history of installed updates. Software Updates consist of incremental updates of the Mac OS and its applications, Security Updates, device drivers and firmware updates. All software updates require the user to enter their administrative password, as with all consequential system changes. Some updates require a system restart. Starting with OS X 10.5, updates that require a reboot log out the user prior to installation and automatically restart the computer when complete; in earlier versions, the updates are installed, but critical files are not replaced until the next system startup. As of OS X Mountain Lion, Software Update has been merged into the Mac App Store.

The Mac App Store was first released in Mac OS X Snow Leopard 10.6.6 on January 6, 2011. The App Store included many applications such as Angry Birds, IWork '09, iLife '11 and Twitter for Mac. On November 3, 2010, Apple was accepting some applications from registered developers for the App Store to include, in preparation for its launch.[121] However, the App Store did not accept applications that required PowerPC code that would be run by Rosetta or if applications required Java SE 6. After 24 hours from release, Apple announced there were one million downloads.

^Spolsky, Joel (June 13, 2004). "How Microsoft Lost the API War". Retrieved April 15, 2009. The developers of the Macintosh OS at Apple have always been in this camp [i.e. not trying to be backwards compatible no matter what]. It's why so few applications from the early days of the Macintosh still work...

^Kelly, Spencer (February 26, 2011). BBC Click programme. BBC. 00:12:45. Retrieved March 20, 2011. "Of course X /ˈɛks/ does mean 10, but anyone who used to poke around on Unix systems will know that in those days anything Unix had an X (ˈɛks) in it, and OS Ten is written OS X (ˈɛks) in honour of the fact that it is based on Unix, unlike its predecessors. So, hey, you can say it any way you want; me, I'm showing my age and sticking with X (ˈɛks).

^Trademark #78257226 for Panther, #78269988 for Tiger, #78270003 for Leopard, #78271630 for Cougar and #78271639 for Lynx, all registered in 2004 by Apple Computer, Inc."United States Patent and Trademark Office". Retrieved December 20, 2006.

^Although the version is now called Cheetah by users, rare evidences can be found to prove that it was called so internally. For instance, a Q&A was created in 2005 which mentions it."Technical Q&A". Apple. October 4, 2005. Retrieved December 20, 2006.